Type: Oral
Session: 721. Allogeneic Transplantation: Conditioning Regimens, Engraftment and Acute Toxicities: Expanding the Donor Pool
Hematology Disease Topics & Pathways:
Biological therapies, AML, Acute Myeloid Malignancies, Diseases, Therapies, Myeloid Malignancies, Transplantation
Methods. The aim of this study was to compare the graft-relapse-free survival (GRFS) for patients diagnosed with acute myeloid leukemia (AML) in first complete remission (CR1), aged 50y or more, and having received a first allo-SCT from a 10/10 MUD younger than 40y or a MRD older than 50y using PTCy for in-vivo T-cell depletion. All transplants were performed between 2015-2021 at the EBMT centres.
Results. A total of 410 consecutive patients were included, 172pts receiving a MRD, 238pts transplanted from a MUD. All patients with detailed conditioning regimen dosages were classified according to the transplant conditioning intensity (TCI) score in low (1-2), intermediate (2.5-3.5), high (4-6). TCI-score was available for 345 patients and was as follows: low in 53pts (36.8%), intermediate in 79pts (54.9%) and high in 12pts (8.3%) for MRD, low in 91pts (45.3%), intermediate in 93pts (46.3%) and high in 17pts (8.5%) for MUD (p=0.26). Only patients with available TCI-score were analysed. In univariate analysis the 2-year GRFS was 58% (49.8-65.3%) for TCI intermediate-high and 43.1% [34.3-51.5] for TCI low (p=0.005). In TCI-score intermediate-high non-relapse mortality (NRM) wasn’t higher compared to TCI-score low (12.7% [12.2-24] vs 13.7% [8.4-20.3], p=0.53) but relapse incidence (RI) was lower (17.7% [12.2-24] vs 33.2% [25.1-41.5], p=0.003). As a strong interaction between TCI-score and type of donor was found, we compared transplant outcomes between MRD and MUD separately for TCI-score low and TCI-score intermediate-high. In TCI-score low, 2-year GRFS was 44.4% [33.5-54.8] for MUD and 40.9% [26.4-54.9] for MRD (p=0.83) (Figure 1A). In multivariable analysis (MVA) type of donor was not a risk factors for neither GRFS (HR 0.98, CI: 0.57-1.69; p=0.95) nor for any other transplant outcome. In TCI-score intermediate-high, 2-year GRFS was 67.2% [55.8-76.2] for MUD and 46.1% [34.4-57.1] for MRD (p=0.001) (Figure 1B). In MVA MUD were associated to better GRFS (HR 0.41, CI: 0.24-0.7; p=0.001), lower NRM (HR 0.19, CI: 0.07-0.55; p=0.002) and lower RI (HR 0.32, CI: 0.14-0.73; p=0.007) without advantages in terms of neither aGvHD nor cGvHD.
Conclusions. In patients with AML in CR1, aged 50y or more and receiving a conditioning regimen with TCI-score ≥ 2.5 in the PTCy setting, a MUD younger than 40y is associated to longer GRFS, lower NRM and lower RI compared to a MRD older than 50y. For patients receiving regimens with TCI-score low transplant outcomes are independent on the type of HLA-matched donor.
Disclosures: Kulagin: Alexion, AstraZeneca Rare Disease, Apellis, Sobi and Generium: Honoraria, Research Funding. Savani: Takeda Development Center Americas, Inc. (TDCA): Current Employment. Mohty: JAZZ PHARMACEUTICALS: Honoraria, Research Funding. Ciceri: ExCellThera: Other: Scientific Advisory Board .